Added an option (-i) to have dump_syms output header information only.

Added an option (-i) to have dump_syms output header information only.

It is often helpful to check if a particular symbol file dumped by
dump_syms actually matches a version of a binary file we have. The
symbol output contains an ID which can be used to see if it matches
the binary file. Unfortunately, this ID is internally calculated
and not a standard hash of the binary file. Being able to output the
header information only will allow users to determine whether their
symbol file is up to date or not.

R=jochen@chromium.org
BUG=561447
Committed: https://chromium.googlesource.com/breakpad/breakpad/+/b0e5f262334e9a4d9e083d0daf430be2202f0152

[jochen (gone - plz use gerrit), 2016-04-06 04:12:45]

lgtm

[David Yen, 2016-04-06 17:10:34]

On 2016/04/06 04:12:45, jochen - slow wrote:
> lgtm

Thanks for the review! I am not a committer, could you land this for me?

[Ted Mielczarek, 2016-04-06 20:55:27]

FYI, the identifier in the MODULE line is not generally a hash on Linux/Mac. On
Linux it's usually the Build ID from the ELF headers, and on Mac it's usually
the UUID from the Mach-O LC_UUID load command. You can read both of these with
standard tools, like on Linux:
readelf -n $file | grep "Build ID"

or on Mac:
otool -l $file | grep uuid

For Linux you also need to mangle the resulting sha-1 hash bytes into the form
of a UUID, like:
https://github.com/luser/linux-symbol-scraping/blob/master/scrapedebs.py#L63

[David Yen, 2016-04-06 21:12:45]

Description was changed from

==========
Added an option (-i) to have dump_syms output header information only.

It is often helpful to check if a particular symbol file dumped by
dump_syms actually matches a version of a binary file we have. The
symbol output contains a hash which can be used to see if it matches
the binary file. Unfortunately, this hash is internally calculated
and not a standard hash of the binary file. Being able to output the
header information only will allow users to determine whether their
symbol file is up to date or not.

R=jochen@chromium.org
BUG=561447
==========

to

==========
Added an option (-i) to have dump_syms output header information only.

It is often helpful to check if a particular symbol file dumped by
dump_syms actually matches a version of a binary file we have. The
symbol output contains an ID which can be used to see if it matches
the binary file. Unfortunately, this ID is internally calculated
and not a standard hash of the binary file. Being able to output the
header information only will allow users to determine whether their
symbol file is up to date or not.

R=jochen@chromium.org
BUG=561447
==========

[David Yen, 2016-04-06 21:14:54]

On 2016/04/06 20:55:27, Ted Mielczarek wrote:
> FYI, the identifier in the MODULE line is not generally a hash on Linux/Mac.
On
> Linux it's usually the Build ID from the ELF headers, and on Mac it's usually
> the UUID from the Mach-O LC_UUID load command. You can read both of these with
> standard tools, like on Linux:
> readelf -n $file | grep "Build ID"
> 
> or on Mac:
> otool -l $file | grep uuid
> 
> For Linux you also need to mangle the resulting sha-1 hash bytes into the form
> of a UUID, like:
> https://github.com/luser/linux-symbol-scraping/blob/master/scrapedebs.py#L63

Thank you for the information, I've updated the CL description to use the term
ID instead of hash. You're right that it's usually the ID except when it doesn't
exist, then it is the a hash of the .text section of the binary.

This option is still useful even if you can determine how to figure it out for
each platform. This way, there is an easy way to check if a symbol file is up to
date without matching whatever dump_syms is doing for each platform.

[jochen (gone - plz use gerrit), 2016-04-08 02:37:53]

Description was changed from

==========
Added an option (-i) to have dump_syms output header information only.

It is often helpful to check if a particular symbol file dumped by
dump_syms actually matches a version of a binary file we have. The
symbol output contains an ID which can be used to see if it matches
the binary file. Unfortunately, this ID is internally calculated
and not a standard hash of the binary file. Being able to output the
header information only will allow users to determine whether their
symbol file is up to date or not.

R=jochen@chromium.org
BUG=561447
==========

to

==========
Added an option (-i) to have dump_syms output header information only.

It is often helpful to check if a particular symbol file dumped by
dump_syms actually matches a version of a binary file we have. The
symbol output contains an ID which can be used to see if it matches
the binary file. Unfortunately, this ID is internally calculated
and not a standard hash of the binary file. Being able to output the
header information only will allow users to determine whether their
symbol file is up to date or not.

R=jochen@chromium.org
BUG=561447

Committed:
https://chromium.googlesource.com/breakpad/breakpad/+/b0e5f262334e9a4d9e083d0...
==========

[jochen (gone - plz use gerrit), 2016-04-08 02:37:55]

Committed patchset #4 (id:60001) manually as
b0e5f262334e9a4d9e083d0daf430be2202f0152 (presubmit successful).